Hydraulic Circuit Load Sensing Pump Cavitation Cooling
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Solution Overview
Problem
Existing hydraulic systems for public works vehicles operating on the 'load sensing' principle face complexity and inefficiency due to the need for multiple pumps to manage various functions, including boost, scavenging, and control, especially in managing cavitation phenomena and fluid cooling during standby modes.
Innovation Solution
A hydraulic circuit design utilizing a single 'load sensing' pump with a pressure-reducing device, nonreturn valve, and calibrated restriction, which provides simultaneous boost and scavenging functions, ensuring minimum flow for cooling and preventing cavitation, while reducing the number of required hydraulic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple pumps are used to provide boost, scavenging, and control functions, then system reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple pump functions (boost, scavenging, control) into a single hydraulic pump. The main hydraulic pump is equipped with a multi-position directional control valve that can direct fluid flow to serve different functions: boost port for cavitation prevention, scavenging port for cooling, and control circuit port for auxiliary functions. This integration eliminates the need for separate auxiliary pumps while maintaining all necessary functions.
Solution Approach 2:
The single hydraulic pump is designed with universal capability to perform multiple functions through a directional control valve with positions including: main power output, boost output to motor, scavenging output to cooler, and control circuit output. The pump serves as both the main power source and the auxiliary system provider, making it a multi-functional universal component that replaces what would traditionally require multiple specialized pumps.
2Device complexity
If a single pump is used for all functions, then device complexity is reduced, but reliability deteriorates
Solution Approach 1:
The directional control valve associated with the single hydraulic pump is designed with multiple dynamic positions that can be switched based on operating conditions. The valve can dynamically allocate pump output to different functions: directing flow to boost port when cavitation risk exists, to scavenging port when cooling is needed, to control circuits when auxiliary functions are required, or to main power circuits during normal operation. This dynamic adaptability ensures the single pump can reliably handle varying system demands.
Solution Approach 2:
The system utilizes parameter changes in the directional control valve positions to switch between different functional modes. Each valve position changes the pressure and flow parameters directed to different ports of the hydraulic pump, enabling the same pump to operate in different functional states (boost mode, scavenging mode, control mode, power mode) depending on system needs, thereby maintaining reliability through parameter-based functional switching.
3Adaptability or versatility
If two valves are used to manage standby and power circuits, then system adaptability is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple valves into a single multi-position directional control valve. This single valve integrates the capabilities of what would traditionally require separate valves for standby mode, power mode, boost function, scavenging function, and control circuit management. By combining these valve functions into one component, the system achieves the same adaptability with reduced complexity.
Solution Approach 2:
The directional control valve is designed as a universal component that can handle multiple operating modes and functions through its various positions. It universally manages: standby circuit isolation, power circuit activation, boost port activation, scavenging port activation, and control circuit supply. This multi-functional valve design provides system adaptability across all operating conditions without requiring multiple specialized valves.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables efficient operation with a single pump, reducing energy consumption, improving heating rates, and preventing cavitation, while simplifying diagnostics and reducing system size and cost by eliminating the need for auxiliary pumps.
Implementation Method 1
a pressure-reducing device connected to the outlet of said pump and delivering a first pressure level
Implementation Method 2
an assembly connecting a nonreturn valve and a calibrated restriction in parallel
Implementation Method 3
an assembly connecting a nonreturn valve and a calibrated restriction in parallel
Implementation Method 4
a device for cooling the fluid which circulates therein
Implementation Method 5
a hydraulic pump driven by a combustion engine using a 'load sensing' logic
Implementation Method 6
a hydraulic motor, responsible for moving a part of the vehicle
Data Source
AI summary
The invention relates to a hydraulic circuit (20) for public works vehicles. The circuit comprises: a pump (21) which is driven by a heat engine (22) using a load sensing technique; a hydraulic motor (10) which is used to move one part of the vehicle (8) and a set of hydraulic actuators (12-14); at least one distributor (29) which supplies the hydraulic actuators (12-13) in a controlled manner; and a device (45) for cooling the fluid circulating through the circuit. The inventive circuit is characterised in that it comprises: a pressure-reducing device (33) which is connected to the outlet of the pump (21) and which delivers a first pressure level, said device (33) being connected to the feed port (34) of the hydraulic motor (10); and an assembly which connects a check valve (40) and a calibrated orifice (41) in parallel, said assembly being connected downstream of the feed port (34) of the hydraulic motor and the return line (36) of the distributor (29) and upstream of the cooling device (45).